The present application relates to a laser device using a semiconductor laser. Also, the present application relates to an optical pickup and optical disk device including this laser device.
As optical information recording media, disk-like optical information recording media (optical disks) have been widely available in the related art.
In general, a compact disc (CD), a digital versatile disc (DVD), a Blu-ray Disc®, and others have been used.
On the other hand, an optical disk device supporting the optical information recording medium is configured to record various contents, such as music contents and video contents, and various types of information, such as various data for computer, in the optical information recording medium.
In particular, in recent years, the amount of information is increased due to, for example, increased definition of video and increased sound quality of music. Also, an increase of the number of contents to be recorded in one optical information recording medium has been demanded. Therefore, a further increase of the capacity of the optical information recording medium has been demanded.
To this end, an optical information recording medium has been suggested that is configured to three-dimensionally record information in a thickness direction of the optical information recording medium by using a material forming a record pit by causing a two-photon absorption reaction in response to light (for example, refer to Japanese Unexamined Patent Application Publication No. 2005-37658).
With this structure, the capacity of the optical information recording medium can be increased.
Meanwhile, since this two-photon absorption reaction is a phenomenon only occurring in response to light having a large light intensity, a light source having a large intensity of emitted light is preferably used.
Examples of a light source having a large intensity of emitted light include short-pulse light sources, such as so-called picosecond lasers and femtosecond lasers, that output laser light of a short pulse, typified by titanium-sapphire lasers and YAG lasers.
However, since these short-pulse light sources can output short pulses by an operation of an optical component provided outside of a light generator, the size of these light sources is generally large, and their price is also high.
Therefore, it may be impractical to mount a short-pulse light source on an optical disk device.